DOCSLIB.ORG

Arid Lands Pdf.Pdf

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Arid Lands Pdf.Pdf “Probably the most basic fact of desert geomorphology is that running water is by far the most important external agent of landform development .” — McKnight and Hess, p. 530. 1 The Topography of Arid Lands ❖ A Specialized Environment ❖ Running Water in Waterless Regions ❖ Characteristic Desert Surfaces—Ergs, Regs, and Hamadas ❖ The Work of the Wind ❖ Two Characteristic Desert Landform Assemblages in U.S. Deserts ❖ Summary 2 Wind Action Erosion By Wind Aeolian: wind processes; Aeolus was Greek god of winds Wind abrasion: particles carried by wind wear down a surface by impact Deflation: lifting and transport in turbulent suspension by wind of loose particles of soil or regolith from dry ground surfaces Deflation produces blowouts Deflation and water action produce desert pavement ❖ The Work of Wind • Aeolian Erosion – Deflation Sand-blasted – Abrasion rock, or ventifact Wind deflation – Fig. 18-17 and 18-18 4 Wind Action Dust Storms Strong winds in arid and semiarid regions can lift large quantities of fine dust to produce dust storms Dust cloud may be several thousand meters high, and may represent an approaching cold front • Aeolian Transportation (Wind Transportation of Sediment) – Suspension – Saltation and Traction • Creep – Fig. 18-19 6 • Reg—Stony Desert ‘Reg’ – Arabic for “stone” – Desert pavement • Hamada—Barren Bedrock ‘Hamada’ – Arabic for “rock” – Exposed bedrock – Cemented sediments – Fig. 18-16 7 – Rainfall – Fluvial deposition – Vegetation – Fig. 18-4 8 ❖ Running Water in Waterless Regions • Significance of Running Water – Aeolian processes less significant – Sparse vegetation • Overland flow erosion • Surface Water in Deserts – Exotic Streams – Fig. 18-5 9 ❖ A Specialized Environment • Special Conditions in Deserts – Weathering – Soil and regolith -Fig. 18-1 10 • Fluvial Erosion in Arid Lands – Differential Erosion • Hardness of rock layers Hard rock Soft rock – Fig. 18-1 11 – Fig. 18-9. The effects of differential erosion on the Red Cliffs near Gateway in Western Colorado. 12 – Ephemeral Streams – Desert Lakes • Playas • Playa lakes – Fig. 18-6 and 18-7 13 – Desert Stream Channels – Fig. 18-13. Mojave Desert, near Baker, CA. 14 – Fig. 18-8. Dry lake bed (playa) in central Nevada. 15 – Residual Erosional Surfaces • Inselbergs (“island mountains”) – Bornhardts – Fig. 18-10. Kata Tjuta (the Oglas) in the desert of central Australia. 16 – Fig. 18-11. The development of a bornhardt. 17 • Pediments – Fig. 18-12 18 – Piedmont Zone • Alluvial fan – Fig. 18-29 19 • Fluvial Deposition in Arid Lands – Deposits in ephemeral stream channels – Piedmont area • Talus accumulations • Alluvial fans – Fig. 18-14. Idealized cross section of a desert piedmont zone. 20 ❖ Two Characteristic Desert Landform Assemblages in U.S. Deserts – Fig. 18-27 21 • Basin-and-Range Terrain – Ranges – Fig. 18-28 22 Basin and Range Horst moves upward Graben moves downward 23 – Basin • Playa – Fig. 18-30 24 – Basin • Salt pan – Fig. 18-33. Death Valley, CA 25 • Mesa-and-Scarp Terrain – Horizontal layers of rock • Slopes have multiple scarps • Differential weathering – Fig. 18-35 26 27 – Residual landforms • Flat-topped summits in horizontal sedimentary strata • Hard cap rock – Fig. 18-36 28 Plateau Largest formation, with rivers cutting into it. Uplift is as fast as river cutting, which leads to Entrenched Meandering Rivers. 29 Mesa Smaller than a Plateau, larger than a Butte. 30 Mesa – Acoma Sky City A mesa is large enough for settlement. A butte is not. 31 Monument Valley 32 – Fig. 18-37. Mitten Buttes, Monument Valley, AZ. 33 34 Bryce National Park 35 Cave dwellings Softer layers erode, leaving behind large caves. 36 Balancing rock Differential weathering 37 – Arches and Natural Bridges • Minor erosional feature • Combination of weathering and fluvial erosion – Fig. 18-39 38 Arches Differential weatheriing 39 ❖ Characteristic Desert Surfaces—Ergs, Regs, and Hamadas • Erg—A Sea of Sand – ‘Erg’ – Arabic for sand – Fig. 18-15 40 – Badlands • Innumerable ravines and gullies. • Steep slopes. – Fig. 18-38. 41 Arches National Park 42 – Dune Forms (Types) • Barchan • Transverse • Seif – Fig. 18-21 43 – Soil Creep – Impermeable surface – Sand - Fig. 18-2 44 • Aeolian Deposition Animation (Desert Sand Dunes) – Desert Sand Dunes • Vegetation and Dune Stabilization • Dune migration – Fig. 18-20 45 Eolian Landforms Sand Dunes Sand dune: hill or ridge of loose, well- sorted sand shaped by wind and usually capable of downwind motion • Active dunes constantly change form and move • Dunes may be stabilized by vegetation • Sand grains may bounce and move by saltation • Asymmetrical; downwind slip face maintains angle of repose of about 35º • Erg: sea of sand • Reg: desert pavement on top of vast sheets of sand – Barchan in Namibia - Fig. 18-22 47 Sand Dunes Barchan dune: isolated, crescent- shaped pile of sand; points of crescent face downwind Transverse dune: wave- like ridges, transverse (perpendicular) to wind – Seif dunes in Simpson Desert of central Australia - Fig. 18-23 49 Sand Dunes Star dunes: large sand hills with dune crests radiating away from center Parabolic dunes: crescent- shaped, points facing toward wind Coastal blowout dunes have saucer-shaped blowout in center • Major loess deposits of the world. – Fig. 18-26 51 – Loess • Another aeolian feature that can be outside of deserts • Wind-blown silt, fine texture, no horizontal layering – Fig. 18-25 52.
Load more

Recommended publications
  • A New Map of Standardized Terrestrial Ecosystems of Africa
    Major contributors to this publication include: The Association of American Geographers is a nonprofit scientific and educational society with a membership of over 10,500 individuals from more than 60 countries. AAG members are geographers and related professionals who work in the public, private, and academic sectors to advance the theory, methods, and practice of geography. This booklet is published by AAG as a special supplement to the African Geographical Review. The U.S. Geological Survey (USGS) was created in 1879 as a science agency charged with providing information and understanding to help resolve complex natural resource problems across the nation and around the world. The mission of the USGS is to provide relevant, impartial scientific information to 1) describe and understand the Earth, 2) minimize loss of life and property from natural disasters, 3) manage water, biological, energy, and mineral resources, and 4) enhance and protect our quality of life. NatureServe is an international conservation nonprofit dedicated to providing the sci- entific basis for effective conservation action. NatureServe’s network in the Americas includes more than 80 member institutions that collect and maintain a unique body of scientific knowledge about the species and ecosystems. The information products, data management tools, and biodiversity expertise that NatureServe’s scientists, technologists, and other professionals provide help meet local, national, and global conservation needs. The Regional Centre for Mapping of Resources for Development (RCMRD) was es- tablished in Nairobi, Kenya in 1975 to provide quality Geo-Information and allied Information Technology products and services in environmental and resource manage- ment for sustainable development in our member countries and beyond.
    [Show full text]
  • Part 629 – Glossary of Landform and Geologic Terms
    Title 430 – National Soil Survey Handbook Part 629 – Glossary of Landform and Geologic Terms Subpart A – General Information 629.0 Definition and Purpose This glossary provides the NCSS soil survey program, soil scientists, and natural resource specialists with landform, geologic, and related terms and their definitions to— (1) Improve soil landscape description with a standard, single source landform and geologic glossary. (2) Enhance geomorphic content and clarity of soil map unit descriptions by use of accurate, defined terms. (3) Establish consistent geomorphic term usage in soil science and the National Cooperative Soil Survey (NCSS). (4) Provide standard geomorphic definitions for databases and soil survey technical publications. (5) Train soil scientists and related professionals in soils as landscape and geomorphic entities. 629.1 Responsibilities This glossary serves as the official NCSS reference for landform, geologic, and related terms. The staff of the National Soil Survey Center, located in Lincoln, NE, is responsible for maintaining and updating this glossary. Soil Science Division staff and NCSS participants are encouraged to propose additions and changes to the glossary for use in pedon descriptions, soil map unit descriptions, and soil survey publications. The Glossary of Geology (GG, 2005) serves as a major source for many glossary terms. The American Geologic Institute (AGI) granted the USDA Natural Resources Conservation Service (formerly the Soil Conservation Service) permission (in letters dated September 11, 1985, and September 22, 1993) to use existing definitions. Sources of, and modifications to, original definitions are explained immediately below. 629.2 Definitions A. Reference Codes Sources from which definitions were taken, whole or in part, are identified by a code (e.g., GG) following each definition.
    [Show full text]
  • Africa: Physical Geography
    R E S O U R C E L I B R A R Y E N C Y C L O P E D I C E N T RY Africa: Physical Geography Africa has an array of diverse ecosystems, from sandy deserts to lush rain forests. G R A D E S 6 - 12+ S U B J E C T S Biology, Ecology, Earth Science, Geology, Geography, Physical Geography C O N T E N T S 10 Images For the complete encyclopedic entry with media resources, visit: http://www.nationalgeographic.org/encyclopedia/africa-physical-geography/ Africa, the second-largest continent, is bounded by the Mediterranean Sea, the Red Sea, the Indian Ocean, and the Atlantic Ocean. It is divided in half almost equally by the Equator. Africas physical geography, environment and resources, and human geography can be considered separately. Africa has eight major physical regions: the Sahara, the Sahel, the Ethiopian Highlands, the savanna, the Swahili Coast, the rain forest, the African Great Lakes, and Southern Africa. Some of these regions cover large bands of the continent, such as the Sahara and Sahel, while others are isolated areas, such as the Ethiopian Highlands and the Great Lakes. Each of these regions has unique animal and plant communities. Sahara The Sahara is the worlds largest hot desert, covering 8.5 million square kilometers (3.3 million square miles), about the size of the South American country of Brazil. Defining Africa's northern bulge, the Sahara makes up 25 percent of the continent. The Sahara has a number of distinct physical features, including ergs, regs, hamadas, and oases.
    [Show full text]
  • Environmental Impact Assessment (EIA)
    Environmental Impact Assessment (EIA) for the Proposed Construction, Operation and Decommissioning of a Sea Water Reverse Osmosis FINAL EIA REPORT Plant and Associated Infrastructure Proposed at Lovu on the KwaZulu-Natal South Coast CVI Coastal Vulnerability Index DEA Department of Environmental Affairs DP Drift potential EIA Environmental Impact Assessment Edaphic Pertaining to soils ESR Environmental Scoping Report ICMA Integrated Coastal Management Act Mesic “dry”, terrestrial environments Perigeal When the moon is most proximal to the Earth Psammosere Succession stages of a particular stage associated with a dune environment RDD Resultant Drift Direction (a vector addition of wind directions) SLR Sea level rise Seral Pertaining to succession Supra-tidal Above the normal high water mark TWINSPAN Two Way Indicator Species Analysis Copyright 2016 © CSIR – April 2016 Chapter 9, Terrestrial Ecological Assessment, pg 9-1 Environmental Impact Assessment (EIA) for the Proposed Construction, Operation and Decommissioning of a Sea Water Reverse Osmosis FINAL EIA REPORT Plant and Associated Infrastructure Proposed at Lovu on the KwaZulu-Natal South Coast Umgeni Water is considering the establishment of desalination plants at Illovo and Tongaat, within the eThekwini Municipal boundary. These projects entail the abstraction of sea water via a pump system from the marine environment and transfer to a desalination plant, where salts are removed from the water, rendering a potable and consumable product that may be transferred to the water service providers within the region for onward sale to consumers. Brine, a bi-product of the desalination process will be returned to the sea. As a component of the EIA for these proposed projects, a Terrestrial Ecological Assessment has been undertaken to evaluate the likely impacts of the construction, operations and decommissioning phases of the plants in the prevailing terrestrial environments.
    [Show full text]
  • A Geomorphic Classification System
    A Geomorphic Classification System U.S.D.A. Forest Service Geomorphology Working Group Haskins, Donald M.1, Correll, Cynthia S.2, Foster, Richard A.3, Chatoian, John M.4, Fincher, James M.5, Strenger, Steven 6, Keys, James E. Jr.7, Maxwell, James R.8 and King, Thomas 9 February 1998 Version 1.4 1 Forest Geologist, Shasta-Trinity National Forests, Pacific Southwest Region, Redding, CA; 2 Soil Scientist, Range Staff, Washington Office, Prineville, OR; 3 Area Soil Scientist, Chatham Area, Tongass National Forest, Alaska Region, Sitka, AK; 4 Regional Geologist, Pacific Southwest Region, San Francisco, CA; 5 Integrated Resource Inventory Program Manager, Alaska Region, Juneau, AK; 6 Supervisory Soil Scientist, Southwest Region, Albuquerque, NM; 7 Interagency Liaison for Washington Office ECOMAP Group, Southern Region, Atlanta, GA; 8 Water Program Leader, Rocky Mountain Region, Golden, CO; and 9 Geology Program Manager, Washington Office, Washington, DC. A Geomorphic Classification System 1 Table of Contents Abstract .......................................................................................................................................... 5 I. INTRODUCTION................................................................................................................. 6 History of Classification Efforts in the Forest Service ............................................................... 6 History of Development .............................................................................................................. 7 Goals
    [Show full text]
  • Options for Dynamic Coastal Management a Guide for Managers Deltares, Bureau Landwijzer, Rijkswaterstaat Centre for Water Management
    Options for dynamic coastal management A guide for managers Deltares, Bureau Landwijzer, Rijkswaterstaat Centre for Water Management Options for dynamic coastal management A guide for managers Deltares, Bureau Landwijzer, Rijkswaterstaat Centre for Water Management M. Löffler Dr. A.J.F. van der Spek C. van Gelder-Maas 1207724-000 © Deltares, 2013, B 1207724-000-ZKS-0011, Version 2, 8 May 2013, final Contents 1 Introduction 1 1.1 Background 1 1.2 This guide 3 2 Dynamic coastal management 5 2.1 The coastal system 5 2.2 Dynamic coastal management 5 2.3 Policy objectives 6 3 What can be done, and where? 11 3.1 Introduction 11 3.2 What is the initial situation 11 3.3 What are the boundary conditions? 15 3.3.1 Boundary conditions for the purposes of flood protection 15 3.3.2 Boundary conditions associated with other interests 16 3.3.3 Sand budget as a boundary condition 17 4 Options 19 4.1 Introduction 19 4.2 Types of dynamic and their added value 21 4.2.1 Embryonic dunes 21 4.2.2 Blowout foredune 22 4.2.3 Gouged foredune 23 4.2.4 Parabolic foredune 25 4.2.5 Washover 26 4.2.6 Intertidal dune areas (slufters) 27 5 Implementation and planning 29 5.1 Introduction 29 5.2 Communications 29 5.2.1 Current situation 29 5.2.2 Recommendations 30 5.3 Monitoring 31 5.3.1 The goal of the monitoring and questions to be answered 31 5.3.2 The parameters selected for monitoring and the methods and techniques 32 5.3.3 Available databases with monitoring data 33 5.4 Intervention in response to undesirable developments 34 6 References 35 Options for dynamic coastal management A guide for managers i 1207724-000-ZKS-0011, Version 2, 8 May 2013, final 1 Introduction 1.1 Background Dynamic coastal management: again and again, the concept emerges in plans for research, management and policy.
    [Show full text]
  • Geologic Map of the Indian Spring Quadrangle, San Bernardino County, California
    U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Geologic Map of the Indian Spring Quadrangle, San Bernardino County, California by H.G. Wilshire 1 Open-File Report 92-181 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. *345 Middlefield Road MS/975, Menlo Park, CA 94025 GEOLOGIC MAP OF THE INDIAN SPRING QUADRANGLE, SAN BERNARDINO COUNTY, CALIFORNIA INTRODUCTION Eruptive rocks of the Cima volcanic field occur almost entirely within six 7.5 minute quadrangles, Indian Spring, Marl Mountains, Granite Spring, Cow Cove, Solomons Knob, and Valley Wells. The following description applies to all six quadrangles. The Cima volcanic field is a small (-300 km^) Tertiary-Quaternary alkaline basalt field in the Ivanpah highlands (Hewett, 1956), in east-central Mojave Desert (Fig. 1). The basaltic rocks, which range from late Miocene to Holocene, were erupted from at least 71 vents. The younger vents are well-formed cinder cones, whereas older vents are marked by degraded cinder cones, plugs, and crater-fill lava flows. The volcanic rocks were described in a general geologic study by Hewett (1956). The southern part of the field was mapped by Barca (1966), and fie northern part by DeWitt (1980). Topical studies of the volcanic field include the geomorphology of pediment domes (Sharp, 1957; Dohrenwend and others, 1984a,b), geomorphic and soil evolution of the lava flows (Wells and others, 1984; McFadden and others, 1984), paleontology and stratigraphy of Tertiary and Quaternary deposits of the Shadow Valley Basin (Reynolds and Nance, 1988), structural studies (Hewett, 1956; Dunne, 1977; Reynolds, 1990; Skirvin and Wells, 1990), polycyclic volcanism (Renault and Wells, 1990), and evolution of the upper mantle and lower crust beneath Cima based on xenoliths in the basalts (Wilshire, 1990; Wilshire and others, 1991).
    [Show full text]
  • Sand Dune Processes and Management for Flood and Coastal Defence Part 2
    PB11207-CVR.qxd 1/9/05 11:42 AM Page 1 Joint Defra/EA Flood and Coastal Erosion Risk Management R&D Programme Sand dune processes and management for flood and coastal defence Part 2: Sand dune processes and morphology R&D Technical Report FD1302/TR Joint Defra/EA Flood and Coastal Erosion Risk Management R&D Programme Sand dune processes and management for flood and coastal defence Part 2: Sand dune processes and morphology R&D Technical Report FD1392/TR Produced: May 2007 Authors: Kenneth Pye Samantha Saye Simon Blott Statement of use This report provides a summary of research carried out to assess the significance of coastal dune systems for flood risk management in England and Wales, to document the nature of the underlying geomorphological processes involved, and to identify alternative strategies and techniques which can be used to manage coastal dunes primarily for the purposes of coastal flood defence, taking into account nature conservation interests and other uses of coastal dunes. The report considers the general effects of changes in climate and sea level on coastal dune systems, and examines the current problems and options for future management at five example sites. The report is intended to inform local engineers and other coastal managers concerned with practical dune management, and to act as stimulus for further research in this area. Dissemination status Internal: Released internally External: Released to public domain Keywords Coastal flood risk management, natural sea defences, coastal dune management Research contractor: Royal Holloway University of London, and Kenneth Pye Associates Ltd. Crowthorne Enterprise Centre, Old Wokingham Road, CROWTHORNE RG45 6AW.
    [Show full text]
  • Geomorphology of Dune Blowouts, Cape Cod National Seashore, MA
    Geomorphology of Dune Blowouts, Cape Cod National Seashore, MA by Alexander B. Smith August, 2013 Director of Thesis: Paul Gares Major Department: Geography Dune blowouts are common erosional features that develop in dune fields worldwide. At Provincelands dunes in Cape Cod National Seashore, blowouts are eroding into shore parallel transverse dunes and the trailing arms of inland parabolic dunes. High spatial and temporal resolution data was collected with Terrestrial Laser Scanning. This allows for the detailed topographic mapping of blowouts that are monitored through time. Large scale geomorphic changes are driven by high magnitude northerly storm events that occur in the fall and winter seasons. Storm events from various incident angles are being topographically steered into the blowout and areas with increased gradient of slope within the blowouts are eroding more rapidly. Incipient embryo blowouts are developing in the lee of elevated dune crests and potentially become captured through the coalescence of landforms. This embryo capture leads to rapid modifications to the host landform and provides new considerations for the larger blowout evolutionary model. Blowouts are ubiquitous features at Cape Cod National Seashore making this an ideal study and the ability to collect high resolution geomorphic data that has greatly increased our knowledge on blowout evolution. Geomorphology of Dune Blowouts, Cape Cod National Seashore, MA A Thesis Presented To the Faculty of the Department of Geography East Carolina University In Partial Fulfillment of the Requirements for the Degree Masters of Arts by Alexander B. Smith August, 2013 © Alexander B. Smith, 2013 Geomorphology of Dune Blowouts, Cape Cod National Seashore, MA by Alexander B.
    [Show full text]
  • Desert Fayum Fayum Desert Reinvestigated Desert Fayum He Neolithic in Egypt Is Thought to Have Arrived Via Diffusion from an Origin in Southwest Asia
    READ ONLY / NO DOWNLOAD The The The Desert Fayum Desert Fayum Reinvestigated Desert Fayum he Neolithic in Egypt is thought to have arrived via diffusion from an origin in southwest Asia. Reinvestigated TIn this volume, the authors advocate an alter- native approach to understanding the development of food production in Egypt based on the results of The Early to Mid-Holocene Landscape new fieldwork in the Fayum. They present a detailed study of the Fayum archaeological landscape using Archaeology of the Fayum North Shore, Egypt an expanded version of low-level food production to organize observations concerning paleoenviron- ment, socioeconomy, settlement, and mobility. While Reinvestigated domestic plants and animals were indeed introduced to the Fayum from elsewhere, when a number of aspects of the archaeological record are compared, a settlement system is suggested that has no obvious analogues with the Neolithic in southwest Asia. The results obtained from the Fayum are used to assess other contemporary sites in Egypt. A landmark publication for Egyptian prehistory and for the general understand- Edited by ing of cultural and environmental change in North Africa and the Mediterranean. David Wengrow, Professor of Comparative Archaeology Simon J. Holdaway UCL Institute of Archaeology and Willeke Wendrich This book results from a remarkable international collaboration that brings together archaeological and geoarchaeological data to provide a new land- scape understanding of the early to mid-Holocene in the Desert Fayum. The results are of great significance, demonstrating a distinct regional character Holdaway to the adoption of farming and substantiating the wider evidence for a polycen- tric development of the Neolithic in the Middle East.
    [Show full text]
  • Geomorphology and Biogeography of Tropical Deserts - Silvio Carlos Rodrigues, Gelze Serrat De Souza Campos Rodrigues
    TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. IX - Geomorphology and Biogeography of Tropical Deserts - Silvio Carlos Rodrigues, Gelze Serrat de Souza Campos Rodrigues GEOMORPHOLOGY AND BIOGEOGRAPHY OF TROPICAL DESERTS Silvio Carlos Rodrigues Instituto de Geografia, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil Gelze Serrat de Souza Campos Rodrigues Instituto de Geografia, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil Keywords: Tropical deserts, geomorphology, landforms, landscape, morphological systems, eolian process, dune, erg, hamada, inselbergs, playas, climate, temperature, precipitation, continents, latitude, longitude, biogeography, water-balance. Contents 1. Introduction 2. Tropical Deserts 2.1. Geographical Distribution 2.2. Controlling Factors 2.3. Distinguishing Characteristics 2.3.1. Temperature 2.3.2. Precipitation 3. Processes, Landforms and Tropical Desert Typology 3.1. Eolian Processes 3.2. Sandy Deserts 3.2.1. Dunes 3.2.2. Ergs 3.3. Pavement Features 3.3.1. Regs 3.3.2. Wadis and Chotts 3.3.3. Pediments, Playas and Alluvial Fans. 3.3.4. Mountains Features 4. Biogeography of Tropical Deserts 4.1. Biological Adaptation to Aridity 4.1.1. DesertUNESCO Vegetation – EOLSS 4.1.2. Desert Fauna Glossary Bibliography Biographical SketchesSAMPLE CHAPTERS Summary Geomorphology of Tropical Deserts is driven by the dry climatic condition of the environment. The heat provided by the sun reaches the surface and creates a high temperature in days, but at night the temperature falls. This cycle creates the conditions conducive to the physical weathering that predominates in the tropical deserts. Aeolian processes commands the shaping of surfaces, moving sediments provided by the weathering. These conditions occur in a specific area of the Earth near the sub-tropical ©Encyclopedia of Life Support Systems (EOLSS) TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol.
    [Show full text]
  • Alphabetical Glossary of Geomorphology
    International Association of Geomorphologists Association Internationale des Géomorphologues ALPHABETICAL GLOSSARY OF GEOMORPHOLOGY Version 1.0 Prepared for the IAG by Andrew Goudie, July 2014 Suggestions for corrections and additions should be sent to [email protected] Abime A vertical shaft in karstic (limestone) areas Ablation The wasting and removal of material from a rock surface by weathering and erosion, or more specifically from a glacier surface by melting, erosion or calving Ablation till Glacial debris deposited when a glacier melts away Abrasion The mechanical wearing down, scraping, or grinding away of a rock surface by friction, ensuing from collision between particles during their transport in wind, ice, running water, waves or gravity. It is sometimes termed corrosion Abrasion notch An elongated cliff-base hollow (typically 1-2 m high and up to 3m recessed) cut out by abrasion, usually where breaking waves are armed with rock fragments Abrasion platform A smooth, seaward-sloping surface formed by abrasion, extending across a rocky shore and often continuing below low tide level as a broad, very gently sloping surface (plain of marine erosion) formed by long-continued abrasion Abrasion ramp A smooth, seaward-sloping segment formed by abrasion on a rocky shore, usually a few meters wide, close to the cliff base Abyss Either a deep part of the ocean or a ravine or deep gorge Abyssal hill A small hill that rises from the floor of an abyssal plain. They are the most abundant geomorphic structures on the planet Earth, covering more than 30% of the ocean floors Abyssal plain An underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 m.
    [Show full text]